The LTE-Advanced system (also referred to as the LTE-A or IMT-A system), which is an advanced version of the long term evolution (LTE) system, is being standardized as a wireless communication system for fourth-generation cell phones.
For the LTE-A system, a cooperative communication technology for downlinks and uplinks is being studied to provide improved coverage (refer to NPL 1). The cooperative communication technology permits a plurality of base stations to cooperatively transmit or receive data during data transmission/reception between a base station and a mobile station. For cooperative communication through an uplink, in particular, transmission performance can be improved when signals transmitted from a mobile station are received by a plurality of base stations and then combined. The signals received by the base stations are shared through a wired communication system based, for instance, on optical fiber.
FIG. 21 is a schematic diagram illustrating a system to which an uplink cooperative communication (coordinated multi-point reception or CoMP) scheme is applied. In the system depicted in FIG. 21, base stations eNB3, eNB4 exist and are capable of sharing, for example, received data through optical fiber. Further, mobile stations UE5-UE7 exist and communicate with either of the two base stations. A synchronization signal or the like is used to connect the mobile stations UE5-UE7 to a base station that exhibits the highest reception power or signal-to-interference-plus-noise ratio (SINR).
In the communication system depicted in FIG. 21, the mobile stations UE5, UE6 are respectively connected to the base stations eNB3, eNB4. Meanwhile, the mobile station UE7 is connected to both the base stations eNB3, eNB4 as the base stations eNB3, eNB4 are engaged in cooperative communication. However, the mobile station UE7 does not always need to grasp all the base stations engaged in cooperative communication. The mobile station UE7 may receive parameters used for data transmission, as control information, from a particular base station only.
A frequency band used for data transmission by the mobile stations connected to the base stations engaged in cooperative communication is generally determined depending on frequency band use of all base stations engaged in cooperative communication. In other words, the frequency bands to be allocated to the mobile stations connected to each base station are determined so that they are orthogonal to each other on the frequency axis. Hence, in the example depicted in FIG. 21, the base station eNB3 determines a band allocation so that the frequency bands used for data transmission by the mobile stations UE5, UE7 are orthogonal to each other. Meanwhile, the base station eNB4 determines the band allocation so that the frequency bands used for data transmission by the mobile stations UE6, UE7 are orthogonal to each other.